More than 150 firefighters have been involved in a major exercise which focussed on three chemical incidents happening simultaneously.
The scenario included suspected terrorist activity, a multi-vehicle crash, a ship fire, a VIP visit and 50 casualties suffering from exposure to an unknown toxic substance.
The exercise was to test aspects of operational effectiveness, command and resilience of Hampshire and Isle of Wight fire and rescue services.
HFRS Group Manager Brian Rudman said:
“Crews responded extremely well to a challenging and complex scenario that they had limited prior knowledge of.
“Exercises like this are hugely valuable and give a sense of realism it is impossible to replicate in a class room or drill yard.
“I would like to thank all those involved for their help, especially our on-call firefighters for making themselves available, to ensure this happened and their contribution to making life safer.”
Crews were deployed to Petersfield where, according to the scenario, the terrorists had been mixing toxic substances in a garage near council offices.
Neighbours had started to suffer ill effects after being exposed to an unknown chemical substance.
In another part of the scenario a terrorist had been heading to the Isle of Wight by ferry when a fire on board caused the ship to turn back to Southampton Docks.
After passengers disembarked he became alarmed at the police presence and activated a device.
When crews arrived dozens of people have started to show signs of chemical exposure such as rashes and blistered skin.
Meanwhile on the Isle of Wight two terrorists were making their way to the location of the VIPs visit.
However, on the way they are overcome by fumes from the toxic chemicals they are carrying and cause a three-car crash.
There were several people trapped and other causalities affected by the chemicals.
The exercise saw the firefighters treating injured people and decontaminating casualties while several fire ground difficulties and obstacles were added to the scenario.
The exercise also tested command and resilience with other fictitious incidents taking place across the county.
It involved 200 people in total and 30 engines.
Last year's annual exercise included a terror attack and fire.
Hampshire Constabulary and South Central Ambulance Service (SCAS) also took part in the event led by Hampshire Fire and Rescue Service.
Other organisations involved included Associated British Ports, East Hampshire District Council, The Island Technology Park and Rapid Relief Team.